EP0091545A2 - Ellipsometer - Google Patents

Ellipsometer Download PDF

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Publication number
EP0091545A2
EP0091545A2 EP83101543A EP83101543A EP0091545A2 EP 0091545 A2 EP0091545 A2 EP 0091545A2 EP 83101543 A EP83101543 A EP 83101543A EP 83101543 A EP83101543 A EP 83101543A EP 0091545 A2 EP0091545 A2 EP 0091545A2
Authority
EP
European Patent Office
Prior art keywords
ellipsometer
polarization
sample
detector
modulator
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP83101543A
Other languages
English (en)
French (fr)
Other versions
EP0091545A3 (de
Inventor
Jean-Claude Andre Chastang
Walter William Hildenbrand
Menachem Levanoni
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
International Business Machines Corp
Original Assignee
International Business Machines Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by International Business Machines Corp filed Critical International Business Machines Corp
Publication of EP0091545A2 publication Critical patent/EP0091545A2/de
Publication of EP0091545A3 publication Critical patent/EP0091545A3/de
Ceased legal-status Critical Current

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/21—Polarisation-affecting properties
    • G01N21/211—Ellipsometry

Definitions

  • the invention relates to ellipsometers.
  • U S Specification No. 3,741,661 (Yamamoto) describes an ellipsometer capable of measuring the two variables of polarization (angle of elleptical orientation and phase difference) of a polarized light beam after modulation of the beam by a specimen orientated at an arbitary angle. Circularly polarized light is incident on the specimen and the modulated light passed successively through a quarter wave ( )/4) plate, a half wave (X/2) plate, an optical modulator, a Savart plate, and an analyzer before reached a photo detector.
  • the ⁇ /2 and ⁇ /4 plates are rotatably mounted and angularly rotated by two separate servo-motors energised from the output of the photo-detector.
  • the optical modulator comprises a a/2 plate positioned between two electro-optical crystal plates energized by two ⁇ /2 out-of-phase signals and has the effect of rotating the plane(s) of polarization of light passing therethrough.
  • the specimen is set-up and the ellipsometer operated to mechanically move the rotatable ⁇ /2 and ⁇ /4 plates to angular positions in which a predetermined output is detected by the photo-detector. Instruments coupled to the two plates then provide the desired information about elliptical orientation and phase difference. Thereafter the servo-motors are disabled and the Savart plate manually moved to determined the phase difference introduced by the specimen.
  • a practical use for ellipsometers is in the analysis of the surface of a body or of a thin film thereon.
  • the analysis is to be made in the course of a manufacturing process, for example during the formation of a thin film layer on a body, the measurements have to be made very rapidly.
  • Yamamoto ellipsometer and other ellipsometers which require mechanical movement of parts, rapid measurement is difficult and inconvenient to achieve.
  • the present invention is concerned with this problem of making rapid analyses of the surfaces of bodies or films.
  • an ellipsometer that includes a polarization modulator driven in time quadrature at a single frequency.
  • the modulator which consists of an array of two or more uniaxial electro-optic crystals in series is located between the laser source and the sample. The optic axes of the crystals are parallel to the laser beam propagation direction.
  • a quarter wavelength plate is located between the laser and the polarization modulator. The laser beam passes through the quarter wavelength plate and the polarization modulator and strikes the sample at an angle of incidence of, for example, 70°.
  • a 45° analyzer is located between the sample and the detector and receives the beam reflected by the sample.
  • a computer is employed to connect the output of the detector to acquire data at specific times and to analyze the signal.
  • the invention provides an ellipsometer for use with a sample, comprising a source of monochromatic light to provide a beam of light directed at the sample, a quarter wave ( ⁇ /4) plate positioned in the beam path between the source and the specimen, and a detector positioned to receive light from the specimen, said ellipsometer being characterised by the combination of an electro-optical polarization modulator positioned in the beam between the quarter wave plate and the sample and a polarization analyser located in the beam between the sample and the detector, said polarization modular being driven by two separate electrical signals having the same frequency but in time quadrature (i.e. 90° out-of-phase) so that the plane of polarization of the light emerging from the modulator is effectively rotated at the frequency of the applies signals.
  • the ellipsometer 10 for use with a sample 12 includes a laser source 14, for example a helium neon laser, that provides a single plane polarized beam.
  • the beam from the laser source 14 passes through a ⁇ /4 plate 16 suitably oriented as shown in the drawing, resulting in circular polarization.
  • the beam passes through a polarization modulator 18 driven in time quadrature.
  • Modulator 18 converts the polarization of the beam to a state of effective rotation, the frequency of which is determined by its driving circuit.
  • the modulator 18 consists of two (18A and 18B) or more (18C, 18D and 18E) uniaxial electro-optic crystals in series, with their optic axes parallel to the beam propagation direction.
  • the principal dielectric axes of crystal 18B are aligned at 45° with respect to the dielectric axes of crystal 18A.
  • the driving voltages (applied along the optic axis for the longitudinal electro- optic effect) are 90° out of phase with respect to each other (i.e. in time quadrature).
  • the amplitudes V 10 and V 20 are such that the maximum resultant electro- optic retardation is ⁇ /4.
  • the polarization state of the output is not linear, nor does the major axis of the polarization ellipse rotate at a constant frequency.
  • the deviations are small (a few percent in both cases) and do not affect the results at the sampled points.
  • these deviations can be made arbitrarily small if additional crystals 18C, 18D and 18E are used with crystals 18A and 18B.
  • the crystals are connected optically in series and electrically in parallel in an alternating array, so that type 18A crystals occupy odd positions and type 18B crystals occupy even positions in the array. This arrangement has an added advantage of lowering the required drive voltages.
  • the required single crystal drive voltage is reduced by a factor equal to the number of crystals (of that type) in the array.
  • operation of up to 100MHz is possible with less than 50 V drive voltages (laser metrics, model 3032) at the HeNe wavelength.
  • polarization modulated beam coming from polarization modulator 18 is then reflected by the sample 12 through a suitably oriented polarization analyzer 20 to a single photodetector 22.
  • a computer 24 e.g. a stored program data processing apparatus is connected to receive the output of the detector 22 to acquire data at specific times and programmed to analyze the signal.
  • the ellipsometer shown in the figure incorporates the polarizer-analyzer (PSA) arrangement.
  • PSD polarizer-analyzer
  • the photodetector signal I is a function of the polarizer azimuth angle - p (time dependent) and the analyzer azimuth angle - A(fixed). This function is given by the equation
  • I(P,A) K(1-cos2 ⁇ (cos 2A + cos 2P) + cos 2A cos 2P + sin2 W cos A sin 2A sin 2P]
  • K is a proportionality constant and ⁇ and ⁇ are the usual ellipsometric angles.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Acyclic And Carbocyclic Compounds In Medicinal Compositions (AREA)
EP83101543A 1982-04-12 1983-02-18 Ellipsometer Ceased EP0091545A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US36769282A 1982-04-12 1982-04-12
US367692 1982-04-12

Publications (2)

Publication Number Publication Date
EP0091545A2 true EP0091545A2 (de) 1983-10-19
EP0091545A3 EP0091545A3 (de) 1984-08-22

Family

ID=23448212

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83101543A Ceased EP0091545A3 (de) 1982-04-12 1983-02-18 Ellipsometer

Country Status (2)

Country Link
EP (1) EP0091545A3 (de)
JP (1) JPS58182518A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3825683C1 (de) * 1988-07-28 1989-12-28 Erwin Sick Gmbh Optik-Elektronik, 7808 Waldkirch, De
DE4402428C2 (de) * 1993-02-02 2003-06-18 Northern Telecom Ltd Optisches Datenübertragungssystem
DE102006012022A1 (de) * 2006-03-14 2007-09-20 Betriebsforschungsinstitut VDEh - Institut für angewandte Forschung GmbH Verfahren zur Bestimmung der Auflage auf einem bewegten Metallband
CN110596012A (zh) * 2019-09-17 2019-12-20 华中科技大学 一种磁光调制椭偏仪装置及测量方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63204123A (ja) * 1987-02-19 1988-08-23 Hiroshi Kezuka 準偏光角による厚膜，薄膜の光学定数および膜厚の測定方法

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3239671A (en) * 1962-05-21 1966-03-08 Gen Telephone & Elect Single-sideband light modulator
US3272988A (en) * 1963-03-25 1966-09-13 Gen Telephone & Elect Polarization modulation system for transmitting and receiving two independent signals over a single electromagnetic carrier
US3443857A (en) * 1965-03-26 1969-05-13 Bell Telephone Labor Inc Compensated quadratic electro-optic modulator
DE1547446A1 (de) * 1967-01-04 1969-12-04 Siemens Ag Vorrichtung fuer ellipsometrische Untersuchungen
SE358740B (de) * 1967-10-10 1973-08-06 Philips Nv
JPS5010670B1 (de) * 1970-04-16 1975-04-23
US3880524A (en) * 1973-06-25 1975-04-29 Ibm Automatic ellipsometer
JPS5240388A (en) * 1975-09-26 1977-03-29 Nippon Kogaku Kk <Nikon> Spectroscopic autoellipsometer
JPS5414952A (en) * 1977-07-04 1979-02-03 Kao Corp 1-halogenocarbonyltricyclo(4,3,1,12,5)undecane
JPS6042901A (ja) * 1983-08-18 1985-03-07 Matsushita Electric Ind Co Ltd ヘリカルフイルタ

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3825683C1 (de) * 1988-07-28 1989-12-28 Erwin Sick Gmbh Optik-Elektronik, 7808 Waldkirch, De
US5013153A (en) * 1988-07-28 1991-05-07 Erwin Sick Gmbh Optik-Elektronik Interferometric gas component measuring apparatus for small gas molecules
DE4402428C2 (de) * 1993-02-02 2003-06-18 Northern Telecom Ltd Optisches Datenübertragungssystem
DE102006012022A1 (de) * 2006-03-14 2007-09-20 Betriebsforschungsinstitut VDEh - Institut für angewandte Forschung GmbH Verfahren zur Bestimmung der Auflage auf einem bewegten Metallband
CN110596012A (zh) * 2019-09-17 2019-12-20 华中科技大学 一种磁光调制椭偏仪装置及测量方法

Also Published As

Publication number Publication date
JPS58182518A (ja) 1983-10-25
EP0091545A3 (de) 1984-08-22

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Inventor name: CHASTANG, JEAN-CLAUDE ANDRE

Inventor name: HILDENBRAND, WALTER WILLIAM

Inventor name: LEVANONI, MENACHEM